1. Field of the Invention
The present invention relates to a golf club shaft. More particularly, the present invention relates to a golf club shaft made of a fiber reinforced resin.
2. Description of the Related Art
A golf club shaft is divided broadly into a so-called steel shaft and carbon shaft. The carbon shaft is widely used in respects of lightness, a high degree of freedom of design, or the like.
The so-called carbon shaft is made of a fiber reinforced resin. As a manufacturing method of the carbon shaft, a sheet winding method is well known. In the manufacturing method, a sheet-shaped prepreg is wound around a mandrel (cored bar), further a wrapping tape is wound, and then the prepreg is heated to cure the prepreg.
The wrapping tape is spirally wound. After the curing step, the wrapping tape is removed. A large number of irregularities formed by the wrapping tape remain on the surface of a cured tubular body. Surface polishing is applied in order to smooth the irregularities as described in Japanese Patent Application Laid-Open No. 2004-57731.
A head is attached to a tip part of a shaft. A stress in hitting is apt to be concentrated on the tip part of the shaft. In a shaft disclosed in Japanese Patent Application Laid-Open No. 2002-233598, a prepreg for tip reinforcing which has a right triangle shape is used. The prepreg for tip reinforcing is provided on an innermost layer.